Hard facing alloy



HARD nAcrNo ALLoY Peter Paysou, New York, N. Y., and Lloyd F. Bowne, Jr., Livingston, N. .l'., assignors to Crucible Steel Company of America, Pittsburgh, Pa, a corporation of New Jersey N Drawing. Application December 15, 1954, Serial No. 475,565

12 Claims. (Cl. 75-171) This invention pertains to hard facing compositions and alloys adapted to be deposited as an overlay on metal surfaces by welding techniques, and provides compositions and alloys for such applications which are characterized by high hot hardness and high corrosion resistance to molten lead oxide.

It has long been the practice in the manufacture of exhaust valves for heavy duty internal combustion engines for aircraft, trucks, tractors, and buses to provide extra Wear and corrosion resistance at the seating surface of the valves by means of an overlay of a hard corrosion resistant material deposited by welding techniques. The most commonly used materials have been either cobalt base or nickel base alloys with chromium and tungsten. Typical analyses are given in Table I.

TABLE I Conventional hard facing alloys Grade 0 Mn s1 Cr W Fe Ni on These have generally been evaluated by a corrosion test in whichweight loss per unit of area is established for a one hour immersion in molten lead oxide at 1675 F.; and by a hot hardness test at temperatures up to 1600 F. Data for the conventional materials are as follows:

TABLE II Lead oxide corrosion and hot hardness data on conventional hard facing alloys Loss in lead Impact hardness, Brinell, at

oxide at Grade 1 1,675 F.,

1 hr., gms/ 1,200" F. 1,400 F. 1,500 F. 1,600 F. sq. in.

A 80 230 220 210 200 B 1. 0 210 200 190 180 C 90 315 315 300 255 D 40 285 255 255 230 1 See Table I for compositions.

tatcs Patent are shown by the test results of the following Table IV.

Patented Feb. 26, 1957 molten lead oxide, along with high hot hardness. It is a further object of this invention to provide a hard facing composition or alloy that is lower in cost than those that are currently used.

These objectives are broadly achieved in accordance with our invention and discovery through the medium of a hard facing composition or alloy containing as essential constituents about: 1.5 to 3.5% carbon; 15 to 35% chromium, 0.5 to 3% vanadium; 1 to 7.5% of metal of the group tungsten and molybdenum, the tungsten content not to exceed about 6% and the molybdenum content not to exceed about 5%, balance substantially all nickel. The composition or alloy of the invention may also contain optional small additions of other elements such as up to about 5 in aggregate of such metals as cobalt, copper, aluminum, columbium, titanium, boron, and zirconium. In addition, although iron and silicon may be entirely omitted, they are usually present in minimum amounts of 0.1% for silicon and 0.5% for iron. We have found that iron and silicon may be present in amounts up to 15% and up to 1.5% respectively but if the silicon content exceeds 0.5%, the iron content should be at least seven times the silicon content.

The carbide forming elements vanadium, tungsten and/ or molybdenum in small amounts play a vital role in our novel hard facing compositions. and alloys. When about 2% vanadium is present in the composition, some iron may replace nickel therein. This lowers the cost of the composition not only because iron is much cheaper than nickel, but also because when iron is permitted in the composition, some of the chromium and vanadium therein may be added by means of fer-ro-chromium or ferro-vanaldium which are much less expensive than chromium and vanadium metals, respectively.

We have found that the corrosion resistance of alloys in accordance with our invention is excellent when up to about 3% vanadium is present, but when the vanadium is above about 3%, the corrosion resistance deteriorates. On the other hand, the hot hardness of such alloys is not particularly good when the vanadium content is low. These facts are shown by the test results in Table III below.

TABLE In Efiect of vanadium content on corosion resistance and hot hardness of nickel-chromium alloys Heat 0 Si Cr V Fe Ni 1 5 .3 26. 3 0 97 1.0 Balance. 1 9 .1 26. 5 1 2.1 Do. 1 7 .6 26.2 3 54 2.9 Do. 1 b .6 25.5 7 26 2.9 Do.

Weight loss Impact hardness, Brinell, at-

in lead Heat oxide at 1113, l,200 F. 1,400" F. 1,500 I". 1,000 F. g1ns./sq. in.

91 .18 255 230 220 200 1492. 21 240 220 220 200 1493 a a 45 255 240 220 230 I494. 50 255 240 240 240 However, we have found that when limited amounts of tungsten or molybdenum or both, are added to the alloy with up to 3% vanadium, the desired combination of corro s-ion resistance and hot hardness is obtained. These facts TABLE IV Composition, percent \IVeigiht Impart hardness, Brinell, at

use 11 lead Heat oxide in O Si Cr V \V 1W0 Fe Ni 1675 F., 1 1,200 I. 1.400 F. 1,500 F. 1,600 F.

hr., g ms./ sq. in.

1756.. 1.8 .2 26.8 1.83 2. 2 Ba]. 0.15 240 230 210 200 9570-- 1. 8 4 26. 1 2. 38 2. 3 Bill. 0.13 240 230 200 176i. 2. 3 1 27. 3 2. 00 1. 7 13211. 0. 14 270 240 230 220 1757-- 1. 6 2 26. 2 1. 08 5. 0 1. 8 Bal. 0.21 255 255 230 220 1495.. 1. 8 3 26. 3 1. 55 4. 6 0. 9 Ba]. 0. 18 255 240 230 230 1758.- 1. 8 .1 26. 3 1. 88 5. 1 1. 4 E81. 0.23 285 255 240 240 1762-- 2. 3 1 27. 1 2. 04 5. 2 1. 7 B81. 0. 23 285 270 270 240 9573-- 1. 9 3 27. 7 2. 38 5.0 2. 6 B21. 0. 13 270 255 230 1497.- 2.0 4 26.0 3. 44 5. 2 1. 0 Bel. 0.77 270 230 230 230 1498.. 2. 0 3 26.8 7. 24 4. 9 0.8 Bal. 0. 83 300 270 255 240 1759.- l. 8 1 25. 1.07 8. 2 0. 9 Hal. 0. 55 270 270 2 10 240 1760.- 1. 8 1 27. 1 1. 96 8. 2 1. 6 Bill. 0. 73 335 285 285 255 2014... 2.0 1 25.8 2. 08 1. 3 Bill. 0. 285 255 240 230 2015.- 2.0 1 25. 8 2.03 1. 1 Bal. 0. 93 285 255 255 240 2010,- 1. 9 1 25. 8 2.02 1. 0 B211. 1. 28 315 270 240 240 314--. 2. 7 1 27. 7 2. 23 1. 6 E81. 0.19 285 285 270 255 317-.. 3. 0 1 26. 1 1. 90 1. 7 Bal. 0. 17 300 255 240 230 316-.- 2. 5 1 26.0 2. 23 1. 2 Bal. 0. 285 270 255 255 315-.- 3. 1 1 27. 2 2.11 1.1 B81. 0. 24 285 270 255 255 It may be observed in this table that the corrosion rate in lead oxide at 1675 F. is over about 0.25 gms./sq. in./hr. when the vanadium in the alloy is over about 3% (Heats 1497 and 1498); or the tungsten is over about 6% (Heats 1759 and 1760); or the molybdenum is over about 5% (Heats 2015 and 2016). The data show, however, that excellent results are obtained by a combined molybdenum and tungsten content ranging as high as about 7.5% as shown by Heats 315 and 316, provided, as above stated, the tungsten present does not exceed about 6% nor the molybdenum about 5%. These, therefore, constitute the upper limits for these elements in our alloy.

It may be further observed that when tungsten under 6% and molybdenum under 5% are both used along with vanadium up to 3% in the alloy of this invention, a corrosion resistance superior to that of the most corrosion resistant conventional alloy, grade D of Tables I and II, is obtained along with hot hardness close to that of the highest hot hardness conventional alloy, grade C of Tables I and 11.

As may be seen in Table V below, we have found that the iron content of the alloy of this invention may be raised to at least 10% without adversely afiecting the corrosion resistance and hot hardness of the alloy, although when the iron is as high as 17.5%, the corrosion resistance is decreased.

TABLE V Eflect of iron content of corrosion resistance and hot hardness of NiCr-V-W-M0 alloy Composition, percent-balance nickel Heat W C Si 01' V W Mo E0 M0 plus W Weight Impact hardness, Brinell, atloss in lead Heat oxide at 1675; F., 1,200 F. 1,400 F. 1,500 F. 1,600" F.

We therefore set an upper limit of 15% for the iron content of our alloy and a preferred upper limit of 12%. Also, it is difficult to eliminate iron, residual iron which is included as an impurity in other additions normally ranging from 0.5% to under 3%. Accordingly, to permit the addition of at least some of the chromium and/or vanadium by means of term-chromium and ferro-vanadium, the preferred lower limit for iron is about 3%.

Although, as mentioned above, silicon may be omitted from the alloy of the invention, it is difiicult to eliminate it entirely and usually it is present in amounts of 0.1% or greater. Furthermore, we have found that silicon affects the corrosion resistance of the alloy so that when the silicon content exceeds 0.5% additional precautions should be taken. Thus, we have found that when the silicon content is greater than 0.5%, the iron content should be at least seven times the silicon content. Also, even though the iron to silicon ratio is maintained at seven or above, the silicon content should not exceed 1.5% if the weight loss of the alloy in molten lead oxide at 1675" F. is not to exceed 0.25 gram per square inch in one hour. The effect of silicon and of the use of iron and silicon in proportions above 7 to 1 is shown in the following table:

TABLE VI Efiect of silicon and iron on corrosion resistance of Ni-Cr-V alloys Loss in lead Ratio oxide at Heat 0 81 01' V Fe Fe/Sl Ni 1675 F.

(or 1 hr glue/sq. 1n.

L1439.-. 2. 10 72 25. 2 2. 0 0. 8 1. 1 Ba] 41-. 41 L1440.-. 2.15 .96 24.6 1.0 0.6 .62 Ba! .34.50 L1441. 2. 16 1. 26 25. 1 2. 0 0. 6 48 Bill 62-. 64 L1442- 2. 10 1. 52 25.2 1. 9 0. 5 33 Ba] 1. 0-1. 1 1.1443. 2. 13 64 24. 7 1. 9 10. 1 15. 8 Bill 13-. 14 L1444- 2. 24 92 25. 7 2. 0 10. 3 11.2 Bnl. 15-. 19 L1445--. 2. 15 1. 18 25. 7 1. 9 10. 3 8. 7 B81. 18-. 19 111446- 2. 18 1. 46 25. 4 1. 9 10. 4 7. 1 13111 21-. 24

The carbon content of our composition or alloy is upward of 1.5% for the purpose of providing good hot hardness in the alloy, as well as good weldability. However, as may be seen in Tables IV and V, there appears to be a tendency for hot hardness to decrease as the carbon content is raised over about 3% and therefore we prefer an upper limit of 3 for carbon.

The chromiumcontent is held between about 15 and 35% although we generally hold the chromium content within the limits, 25 to 30%.

Nickel forms the balance of the alloy and the preferred alloy is a nickel base alloy, i. e., has a nickel con- 7 .tent in excess of 50%.

Although it has been indicated above that cobalt in small amounts may be included in the alloy of the invention, it has been found that cobalt is not the equivalent of nickel in the alloy. For example, the following table shows that when nickel is replaced by cobalt the corrosion resistance is greatly reduced:

TABLE VII Efieci of replacement of nickel by cobalt In considering the above data it should be noted that although vanadium, tungsten and molybdenum have been omitted from the alloys, it has been found that the addition of these elements does not improve the corrosion resistance of the alloys of the invention.

The alloy of our invention is made in an electric furnace, either of the induction or are type. Thealloy is generally cast into small diameter rods. In making the overlay, these rods are melted down by oxyacetylene flame, or by the shielded inert gas metallic arc technique. The rod may also be used as an electrode in arc welding. Furthermore, the rod may be coated and part of the alloy content of the deposit may be provided in the coating. Our alloy may also be deposited from a tube rod of which the tubing is made from nickel strip filled with a powdered admixture of our hard facing composition. Finally, our composition may also be provided in the form of a powdered admixture for application by means of spray gun.

Our invention, therefore, comprises a hard facing composition or alloy of good corrosion resistance and hot hardness as deposited, said alloy comprising:

As above stated, this composition may be provided as a cast alloy rod or as a powder containing all the elements listed above; or it may be provided as a coated electrode which has some of the alloy in the rod and some in the coating so that the deposit will be within the limits set forth; or it may be provided as a tube rod consisting of a nickel tube containing the other elements in the form of powdered metals or ferro alloys, or may be provided as a powdered admixture of the above constituents for use in spray guns. In any case, the Weld deposit will result in an alloy of the above analysis.

This application is a continuation-in-part of our joint parent application Serial No. 402,820, filed January 7, 1954 and now abandoned.

What is claimed is:

1. A hard facing composition consisting essentially of about: 1.5 to 3.5% carbon; to chromium; 0.5 to 3% vanadium; 1 to 7.5% of metal of the group consisting of tungsten and molybdenum; up to 15% iron; balance substantially nickel, characterized in having a weight loss when immersed in molten lead oxide at 6 1675 F.for one hour, of not to exceed 0.25 grams per squareinch, and in having an impact hardness at 1600 F. of not under 230 Brinell. Y

2. A hard facing composition containing about: 1.5 to 3.5% carbon; 15 to 35% chromium; I 0.5 to 3% vanadium; 1 to 7.5% of metal of the group consisting of tungsten and molybdenum, the tungsten and molybdenum contents not to exceed about 6% and 5%, respec tively; up to 1% manganese; up to 15% iron; up to 1.5% silicon, the iron content being at least seven times the silicon content when the silicon content exceeds 0.5%; balance substantially nickel, characterized in havinga weight loss when immersed in molten lead oxide at 1675 F. for one hour, of not to exceed 0.25 grams per square inch, andin having an impact hardness at 1600 F. of not under 230 Brinell.

3. A hard facing composition containing about: 2 to 3% carbon; 25 to 30% chromium; 1 to 2.5% vanadium;

1 to 3.5% tungsten;.1 to 2.5% molybdenum; 3% to 12% 7 iron; up to 1.5% silicon, the iron content being at least seven times the silicon content whenthe silicon content exceeds 0.5%; up to 0.75% manganese; balance sub stantially nickel, characterized inhaving a weight loss when immersed in molten lead oxide at 1675 F. for one hour, of not to exceed 0.25 grams per square inch, and in having an impact hardness at 1600 F. of not under 230 Brinell.

4. A hard facing composition consisting of: 1.5 to 3.5 carbon; 15 to 35 %'chromium; 0.5 to 3% vanadium; 1 to 7.5% of metal of the group tungsten and molybdenum, the tungsten and molybdenum content not to exceed 6% and 5%, respectively; up to 15% iron; up to 1.5% silicon, the iron content being at least seven times the silicon content when the silicon content exceeds 0.5 up to 1% manganese; up to 5% in aggregate of the metals cobalt, copper, aluminum, columbium, titanium, boron, and zirconium; balance nickel.

5. A hard facing composition consisting of: 1.5 to 3.5% carbon; 15 to 35% chromium; 0.5 to 3% vanadium; 1 to 6% tungsten; 1 to 5% molybdenum, the combined tungsten and molybdenum content not to exceed 7.5 up to 15 iron; up to 1.5% silicon, the iron content being at least seven times the silicon content when the silicon content exceeds 0.5%; up to 1% manganese; up to 5% in aggregate of the metals cobalt, copper, aluminum, columbium, titanium, boron, and zirconium; balance nickel.

6. A hard facing composition consisting of: 2 to 3% carbon; 25 to 30% chromium; 1 to 2.5% vanadium; 1 to 3.5% tungsten; 1 to 2.5% rolybdenum; 3 to 12% iron; up to 1.5% silicon, the iron content being at least seven times the silicon content when the silicon content exceeds 0.5%; up to 0.75 manganese; balance nickel.

7. A nickel-base alloy containing about: 2 to 3% carbon; 25 to 30% chromium; 1 to 2.5% vanadium; 2 to 5% of metal of the group tungsten and molybdenum, the tungsten and molybdenum being present in the ranges 1 to 3.5% and 1 to 2.5% respectively; 3 to 12% iron; up to 1.5% silicon, the iron content being at least 7 times the silicon content when the silicon content exceeds 0.5%; up to 1% manganese; up to 5% in aggregate of the metals cobalt, copper, aluminum, columbium, titanium, boron, and zirconium; balance substantially nickel, said alloy being characterized by a weight loss when immersed in molten lead oxide at 1675 for one hour not exceeding 0.25 gram per square inch and by an impact hardness at 1600 F. of not under 230 Brinell.

8. A hard facing composition containing about: 1.5 to 3.5% carbon; 15 to 35% chromium; 0.5 to 3% vanadium; 1 to 7.5 of metal of the group consisting of tungsten and molybdenum, the tungsten and molybdenum contents not to exceed about 6% and 5 respectively; up to 1% manganese; up to 15 iron; up to 0.5% silicon; up to 5% in aggregate of the metals cobalt, copper,

weight loss when immersed in molten lead oxide at 1675 for one hour, of not to exceed 0.25 gram per square inch, and in having an impact hardness at 1600 E. of not under 230 Brinell. y

9Q A hard facing composition containing about: 2 to 3% carbon; 25 to 30% chromium; 1 to 2.5 vanadium; 1 to 3.5% tungsten; 1 to 2.5% molybdenum; 3 to 12% iron; up to 0.5% silicon; up to 0.75% manganese; balance substantially nickel, characterized in having a weight loss when immersed in molten lead oxide at 1675 F. for one hour, of not to exceed 0.25 gram per square inch, and in having an impact hardness at 1600 of not under. 230 Brinell.

10. A hard facing composition containing about: "1.5 to 3.5% carbon; 15 to 35% chromium; 0.5 to 3% vanadium; 1 to 7.5% of metal of the group consisting of tungsten and molybdenum; 0.5 to 1.5% silicon; iron at least seven times the silicon content but not over 15%; balance substantially nickel, characterized in having a weight loss when immersed in molten lead oxide at 1675 F. for one hour, of not to exceed 0.25 gram per square inch, and in having an impact hardness at 1600 F. of not under. 230 Brinell.

11. A hard facing composition containing about: 1.5 to 3.5% carbon; 15 to 35% chromium; 0.5 to 3% vanadium; 1 to 7.5% of metal of the group consisting of tungsten and molybdenum, the tungsten and molybdenum contents not to exceed about 6% and 5%, respectively; up to 1% manganese; 0.5 to 1.5% silicon; iron at least seven times the silicon content but not over 15%; balance substantially nickel, characterized in having a weight loss when immersed in molten lead oxide at 1675 F. of one hour, of not to exceed 0.25 gram per square inch, and in having an impact hardness at 1600 F. of not under 230 Brinell.

12. A hard facing composition consisting of: 1.5 to 3.5% carbon; 15 to 35% chromium; 0.5 to 3% vanadium; 1 to 7.5% of metal of the group tungsten and molybdenum, the tungsten and molybdenum content not to exceed 6% and 5%, respectively; 0.5 to 1.5% silicon; iron at least seven times the silicon content but not over 15%; up to 1% manganese; up to 5% in aggregate of the metals cobalt, copper, aluminum, columbium, titanium, boron, and zirconium; balance nickel.

References Cited in the file of this patent UNITED STATES PATENTS 1,572,996 Girin Feb. 16, 1926 FOREIGN PATENTS 642,669 Great Britain Sept. 6, 1950 494,621 Canada July 21, 1953 OTHER REFERENCES High temperature alloys for rotor blades, Metal Progress, April 1952, pp. 148 and 150. 

1. A HARD FACING COMPOSITION CONSISTING ESSENTIALLY OF ABOUT: 1.5 TO 3.5% CARBON; 15 TO 35% CHROMIUM; 0.5 TO 3% VANADIUM; 1 TO 7.5% OF METAL OF THE GROUP CONSISTING OF TUNGSTEN AND MOLYBDENUM; UP TO 15% IRON; BALANCE SUBSTANTIALLY NICKEL, CHARACTERIZED IN HAVING A WEIGHT LOSS WHEN IMMERSED IN MOLTEN LED OXIDE AT 1675*F. FOR ONE HOUR, OF NOT TO EXCEED 0.25 GRAMS PER SQUARE INCH, AND IN HAVING AN IMPACT HARDNESS AT 1600* F. OF NOT UNDER 230 BRINELL. 